Benthicore
Elemental Mastery
Xenograft

   Prerequisites

What do I need to start this combo?
All permanents on the battlefield.
Elemental Mastery attached to Benthicore. "Merfolk" chosen with Xenograft. Benthicore does not have summoning sickness.

   Steps

How does this combo work?
1
Activate Benthicore by tapping it, creating five 1/1 Elemental tokens with haste that are also Merfolks due to Xenograft.
2
Activate Benthicore by tapping two Elemental tokens, untapping Benthicore.
3
Repeat.

   Results

What do I get from this combo?
Infinite creature tokens with haste
Infinite ETB